The industrial oil market is continuing to grow at a rapid pace. Accompanying this growth is the demand for better lubricant properties, due to more severe operating conditions and the need for better pollution control. Wear-resistant oils and heavy duty, antileak industrial gear oils can alleviate the equipment problems and failures caused by increased pressures and temperatures, shock loading, reduced tolerances, etc. Antileak oils can decrease the undesirable loss of lubricants both in closed hydraulic systems and in open gears. Not only do these latter oils reduce consumption, but they help curb the pollution of our natural waters.
This invention is primarily concerned with one specific area, that of antileak lubricants. By reducing leakage at the source, waste oil can be greatly minimized. However, other properties must not be sacrificed to the degree that lubrication and machinery protection are not satisfactory [see "Cutting Fluids", Lubrication 42 (4), 49 to 60 (1956)]. The present antileak lubricants help control pollution and are also completely satisfactory from the standpoint of other performance requirements (e.g., oxidation stability). With respect to oxidation stability, the degree of stability which is obtained by oxidation inhibitor additives (such as the amine, phenolic and metal dithiophosphate additives), is governed by the end use of the lubricant, e.g., gear oils generally require a lower additive concentration than do hydraulic oils). In any event, the present invention provides improved stability, at a given level of a given additive, compared to similar prior art lubricants.